Catalytic cracking of diisobutylene



Feb. 28,1950 F. B. JOHNSON 2,498,840

CATALYTIC CRACKING OF DIISOBUTYLENE Filed Nov. 14,. 1947 Fe Taz,

BSMM-bborneg Prasad rei. ze, ieso CATALYTIC CBACKINGOF DIISOBUTYLENE lrankB. Johnson, Batonllomligalslgnorto Standard Oil Development ration of Delaware Compaxmaoorp Anuman Nomina i4, 1m, seal No. 'nam l a 'I'his invention pertains to catalytic cracking and particularly to the catalytic cracking o! diisobutylene to produce isobutylene.

The cracking of dilsobutylene to produce isobutylene and the catalytic cracking of hydrocarbon oils such as gas oil to lower boiling materials such as motor fuel are well known and-present no particular problems when carried out sepa.

rately in equipment designed for the particular vpurpose under carefully controlled conditions.

When, however, an attempt was made to crack diisobutylene to isobutylene simultaneously with the cracking of liquid hydrocarbons such as gas oil to motor fuels and the like, substantial dimculties were encountered. The yields of isobutylene were too low to be commercially attractive, the selectivity was relatively poor resulting in low ratios oi' isobutylene to other cracked products such as normal butane and isobutane from the diisobutylene. The inclusion of diisobutylene in the gas oil feed to a catalytic cracking unit also had adverse effects upon the gas oil cracking, lower yields of motor fuels were pro-- duced in some cases and in other cases, particularly with fresh or highly active catalysts, the carbon lformation was appreciably greater when dimer was incorporated in the gas oil feed.

It is the object of this invention to provide the art with a novel method for cracking diisobutylene to isobutylene simultaneously with the cracking of higher boiling hydrocarbon oils such as gas oil to motor fuels.

It is also the object of this invention to so integrate the.cracking of diisobutylene with the catalytic cracking of liquid hydrocarbons that the cracking of both stocks will proceed in the desired manner.

These and other objects will appear more clearly from the detailed specification and claims which follow.

I have now found that diisobutylene can be cracked to isobutylene simultaneously with the catalytic cracking of hydrocarbon oils to motor fuels in the same reaction equipment provided that the cracking is eii'ected in a fluid catalyst cracking unit, preferably one containing a relatively dense catalyst phase in the lower part of the reaction vessel and a disperse or dilute catalyst phase in the upper portion of thereaction vessel. I have found -that if the diisobutylene is introduced in'to the reaction vessel at or closely adjacent the dense bed-disperse phase interface it can be cracked at high conversions and with good selectivity and without any adverse effects upon the cracking of the gas oil or other liquidl 'e hydrocarbon.

In the drawing, the figure represents a diagrammatic flow plan of the process according to the present invention.

Referring now to the drawing, the reference 6 Claims. (Cl. IIB-52) character Il designates the reaction vessel which is cylindrical in form and provided with an inlet line II for introducing a mixture of hydrocarbons in vapor form or partly in vapor form and catalysvt or contact particles. 'I'he hydrocarbon feed stocks can be gas oil, reduced crude oil, whole crude petroleum oil, heavy naphtha, etc. 'Ihe hydrocarbon feed stock is supplied to the inlet II through line I2 from suitable preheatingor vaporizing equipment (not shown), in liquid, in vapor or partly in liquid and partly in vapor form.

The catalyst or contact particles are withdrawn in heated condition from the regenerator I3 through line I4 and introduced into the inlet line II by means of the standpipe I5 in known manner. The heated catalyst particles serve to eect vaporization of the feed stock and bring the mixture up 'to reaction or cracking temperatures. 'I'he suspension of solid catalyst particles in vaporized hydrocarbons is passed upwardly through line II into suitable distributing means I6 arranged at the bottom portion of the reaction vessel III.

'I'he distributing means I8 is provided with a horizontally disposed perforated circular plate which is arranged centrally with respect to the reaction lvessel. The diameter of the perforated plate and theentire distributing means is less than the internal diameter of the reaction vessel III in order that an annular passageway I'l may be provided between the distributing means I6 and the wall of the reaction vessel for the withdrawal of catalyst particles. This annular passageway may be provided with suitable baille means and inlets I8 may also be provided for the supply of steam or other gaseous stripping agent to lsaid passageway in known manner for the purpose of removing adsorbed hydrocarbon materials from the catalyst particles before they are discharged from the bottom of/Ithe reaction vessel into the standpipe I9 and thence into line 20 where they are picked up by a stream of air and carried into the regenerator I3 where the carbonaceous deposits are burned off and. the catalyst particles conditioned for recycling to the reaction vessel I0.

The velocity of the hydrocarbon vapors passing upwardly into the reaction zone or vessel I0 through the perforated plate at the top of the distributing means I6 is preferably selected to maintain the solid catalyst particles in a dense. iluidized. liquid-simulating dry mixture or dense bed ZI. 'I'his mobile, turbulent mass or mixture insures .intimate contact between hydrocarbon vapors and the catalyst or contact'particles. As the vaporous reaction products leave the dense bed 2|, they entrain a small amount of solidparticles forming a dilute suspension or disperse the cracking. catalyst comprises anyV suitable cracking catalyst such as acid-treated bentonite clay, synthetic silica-alumina gel, synthetic silica-magnesia gel, `synthetic silica-aluminamagnesia gel, etc. The catalyst is preferably in powdered or nely divided form in which the particles have a size between about 100 and 400 standard mesh. The preferred catalyst comprises microsphericalI particles of which about 95% passes through a 100 standard mesh sieve and the mixture contains less than 35% preferably about 5-10% of 0-20 micron material. With such a catalyst, .the velocity of the gaseous iluid passing upwardly through the dense bed 2| is about 0.5. to 2.0 ft./second and under these velocity conditions the density of the material forming the dense bed 2l is about 5 to 401bS./cu. ft.

In order to crack diisobutylene simultaneously with the cracking of gas oil or other high boiling hydrocarbon, diisobutylene feed is supplied, preferably preheated to about reaction temperatures to the reaction vessel I0 through feed line 23. As shown the feed line 23 connects with three valved inlets to the reactor, the lower inlet entering the dense phase 2|, the intermediate inlet entering the reactor at the interface between the. dense phase and the dilute .phase and -the top inlet entering the dilute phase 22. While I have shown but a single inlet at each of the three levels, it will be understood that a plurality of inlets may be provided at each level, that inlets at more than three levels can be provided and that further it is within the scope of this invention to introduce the diisofluid catalytic cracking unit alone and with a.

4 or the like which serves to separate most oi the entrained solid catalyst, particles. The separated solid particles are returned to the dense bed through line which extends below the top surface of the dense bed 2|. The vaporous reaction products leaving the separating means 24 pass overhead through line 2l whence they may be passed to anysuitable fractionating equip- 29.8 API, 50% point 0I 700 F. and 1.7% 0fwhich is distilled at 430 F. was cracked. in a commercial grade of isobutylene polymer (anl alysis 90% dimer, 9% codimer and 1% trimer) butylene at two or more levels simultaneously at the same or at different rates. Ordinarily I prefer to introduce the diisobutylene. at the interface between the dense bed and the disperse phase. Introduction of the dimer feed at or above the interface has the furtherA advantage of avoiding an entrainment problem. In other words if the dimer feed is added to the dense bed, the total vapor velocity through the dense bed is increased and entrainment of catalyst fines is increased whereas if the dimer is added at or above the interface the vapor velocity through the dense bed is unaffected and entrainment will be substantially the same as if no dimer was added to the system. Instead of diisobutylene per se, I may use various commercial products which contain a major proportion of diisobutylene. Typical of such products are a mixture containing 90% diisobutylene, 9% of codimer (isobutylene-n-butylene copolymer) and 1% trimer as well as mixtures containing about 65% of dimer and codimer and about 35% trimer. These materials, will be referred to hereinafter as normally liquid polymers of isobutylene.

The amount of polymer that can be injected into the disperse phase in the reactor should not exceed about volume per cent based upon the high boiling liquid hydrocarbon feed stock or gas oil and preferably represents about 10-20 volume per cent. Y Y' The vaporous'reaction products and entrained action vessel Ill through a cyclone separator 2l added in the gas oil feed as well as injected directly into the reactor. 'I'he catalyst used was a synthetic silica-alumina gel catalyst containing about 12% alumina and the cracking temperature in each case was 975 F. The results obtained on these runs are summarized in the following table:

Feed Stock Vol. Percent:

ecs o1 100 07.1 09.9 00.2 Dimer. 0 12.9 10.4 0.8 Point ci Dimer Injection (l) (3) Conversion Level, Percent on Gas Oil 51 Yields, Basis Total Feed:

arbcn Wt. Percent 1.3 1.3 1.3 1.4 Total d., vox. Percent.. 15.8 21.4 90.4 19.0 Iso-04H0, Vol. Percent- 4.0 9.1 9.2 9.2 n-CHl Vol. Percent-- 6.5A 6.2 6.2 5.2 -Ci 10 V01. Percent--- 4.4 7.3 4.4 4.0 n-o.H..vc1.Pe1-ccnt 0.9 0.8 0.6 0.a ry Gas, Wt. Percent 7.9 7.9 7.5 7.3 10# Motor Gaso Vol Percent. 39.9 36.2 38.1 38.6 YieldsI Basis Gas Oil Carbon Wt. Percent 1.3 1.5 1.5 1.4 'rctnx d., Vol. Percent. 15.8 26.9 22.8 21.1 Iso-Clvvol. Petcent. 4.0 10.5 10.3 10.2 n-ClHg, ol. Percent 6.5 7.1 6.9 5.8 Iso-04H10 Vol. Percent 4.4 8.4' 4.9 4.4 n-CHm, Vol. Percent 0.9 0.9 0.1 0.1 Dry Gas, Wt. Percent 7.9 8.8 8.2 '7.9 l0# Motor Gasoline, Vol. Percent 39. 41. 5 42. 6 42.8 Vol. Percent conversion ofDimer to Iso-CHg. 44.2 54.3 57.4 Vol. Percent Iso-CaHrinTotal C4 Fraction..- 25.3 39.1 45.2 48.4 10# Motor Gasoline Inspections:

Percent D-i-L at 158 F... 29.0 32.5 30.0 29. 0 Percent D+L at 212 F..- 55.0 55.0 55. 5 56. Percent D+L at 251 F--- 68.0 65.0 115.5 66.0 0F -Rca octane No.(c1cnr) 95.3 05.3 96.6 95.03

l With oil feed. 2 Point of injection calculated to be about 3 in. below top of dense bgdoint of injection calculated to be about 3 in. above top of dense These results show that the addition of dimer y to wide-cut gas oil feed increased isobutylene yield (based on gas oil feed) from 4.0 percent to about 10 per cent. On a total feed basis carbon yields are roughly the same for the gas-oil and for the gas-oil-dimer mixed feed.

Injection of the dimer into the disperse phase in the reactor zone gave appreciably better results than were obtained when the dimer was added with the gas-oil feed, giving higher con- .version to isobutylene, with greater selectivity (less formation of isobutane and n-butane), higher concentrations of isobutylene in the C4 fraction and lower dry gas formation.

Gasoline yields are comparable (based on total feed) for the dimer-gas oil operation and for gas oil cracking alone. Gasoline octanes were about the same to 1.3 points higher when dimer was mixed in the feed and gasoline volatility was about the same as that obtained with straight tion has no detrimental eii'ects,l upon regular gas .75 011 cracking operations.

The foregoing description contains a limited number of embodiments of the present invention. It will be understood, however, that numerous variations are possible without departing from the scope of this invention as defined in the following claims.

What I claim and desire to secure by Letters Patent is:

1. In the method of cracking higher boilinghydrocarbons bypassing them upwardly through a mass of solid contactv particles which catalyst nuidized liquid like condition in the lower porinterface in order to subject said diisobutylene to relatively milder cracking conditions than the particles vare maintained in a dense phase, dry

iiuidized liquid like condition in the lower portion of a reaction zone and in a dilute phaseili tion of a reaction zone and in a dilute phase-in- 'i the upper portion of the reaction zone, the step which comprises injecting up to about 50 volume per cent based upon the higher boiling hydrocarbon feed of a normally liquid isobutylene polymer into the reactor at a level not below the dense-phase-dilute phase interface in order to subject said polymer to relatively milder cracking conditions than the higher boiling hydrocarbon feed stock is subjected to and to crack said polymer principally to isobutylene.

3. In the method of cracking higher boiling hydrocarbons by passing them upwardly through a mass of solid contact particles which catalyst particles are maintained in a dense phase. dry fluidized liquid likefcondition in the lower portion of a reaction zone and in a dilute phase in the upper` portion of the reaction zone, the step which comprises injecting diisobutylene into the'reactor at. a level not below the dense phase-dilute phase interface in order to subject said diisobutylene to relatively milder cracking conditions than the higher boilinghydrocarbon feed stock is subjected to and to crack said diisobutylene principally to isobutylene.

4. In the method of cracking higher boiling hydrocarbons by passing them upwardly through a mass of solid contact particles which catalyst higher boiling hydrocarbon feed stock is subjected to and to crack said diisobutylene principally to isobutylene.

5. In the method of cracking higher boiling hydrocarbons by passing them upwardly through a mass of solid contact particles which catalyst particles are maintained in a dense phase, dry iluidized liquid like condition in the lower portion of a reaction zone and in a dilute phase in the upper portion of the reaction zone, the stepwhich comprises injecting `10 to 20 volume per cent based upon the higher boiling hydrocarbon feed of a normally liquid isobutylene polymer into the reactor at a level not below the dense phase-dilute phase interface in order to subject said polymer vto relatively milder cracking conditions thanthehigher boiling hydrocarbon feed stock is subjected to and to crack said polymer principally to isobutylene.

6. In the method of cracking higher boiling hydrocarbons by passing them upwardly through a mass of solid contact particles which catalyst particles are maintained in a dense phase, dry fluidized liquid like condition in the lower portion of the reaction zone and in a dilute phase in the upper portion of a reaction zone, the step which comprises injecting 10 to 20 volume per cent based upon the higherboiling hydrocarbon feed of diisobutylene into the-reactor at a level not below the dense phase-dilutev phase interface in order to subject said diisobutylene to relatively milder cracking conditions than the higher boiling hydrocarbon feed stock is subjected to and to crack said diisobutylene principally to isobutylene.- y

FRANK B. JOHNSON.

REFERENCES crrEn The following references are of record in the ille of thispatent:

UNITED STATES PATENTS Number Name Date 2,349,160 Frey et al. 'May 16, 1944 2,356,697 Rial Aug. 22, 1944 2,385,326 Bailey, Jr Sept. '25, 1945 2,416,608 Brackenbury Feb. 25, 1947 particles aremaintainedin a dense phase, dry 

1. IN THE METHOD OF CRACKING HIGHER BOILING HYDROCARBONS BY PASSING THEM UPWARDLY THROUGH A MASS OF SOLID CONTACT PARTICLES WHICH CATALYST PARTICLES ARE MAINTAINED IN A DENSE PHASE, DRY FLUIDIZED LIQUID LIKE CONDITION IN THE LOWER PORTION OF A REACTION ZONE AND IN A DILUTE PHASE IN THE UPPER PORTION OF THE REACTION ZONE, THE STEP WHICH COMPRISES INJECTING A NORMALLY LIQUID ISOBUTYLENE POLYMER INTO THE REACTOR AT A LEVEL NOT BELOW THE DENSE-PHASE DILUTE PHASE INTERFACE IN ORDER TO SUBJECT SAID POLYMER TO RELATIVELY MILDER CRACKING CONDITIONS THAN THE HIGHER BOILING HYDROCARBON FEED STOCK IS SUBJECTED TO AND TO CRACK SAID POLYMER PRINCIPALLY TO ISOBUTYLENE. 